PurposeDrawing on the stakeholder theory, this study aims to empirically analyse the impact of platform enterprises' corporate social responsibility (CSR) announcements on corporate stock market value. This study also estimates the moderating effect of stakeholder orientation and responsibility categories of CSR announcements, the platform enterprise type and the degree of CSR disclosure.Design/methodology/approachThe event study method is used to analyse the change in stock market value of 191 CSR announcements from 137 Chinese platform enterprises. In addition, a case analysis is presented for two platform enterprises with the best practices to validate and complement study findings.FindingsCSR announcements improve platform enterprises' stock market value. Specifically, CSR announcements responding to platform enterprises' external stakeholders, and CSR announcements with economic responsibility, have obvious positive impacts on stock market value. Furthermore, the maker platform's CSR announcement has a more positive impact on stock market value than the exchange platform.Originality/valueTo the best of the authors' knowledge, this study is the first attempt to identify the link between platform enterprises' CSR announcements and stock market performance by empirical evidence, and it contributes to new knowledge of operating and evaluating platform enterprises' CSR.